The clinical features, arteriographic findings, and treatment of 81 patients with spinal arteriovenous malformations demonstrated that there are distinguishing clinical features in patients with arteriovenous malformations of the spinal cord compared to those of patients with arteriovenous fistulas of the spinal dura. The findings indicate that spinal arteriovenous fistulas are acquired lesions, and not congenital, as was previously thought, and support arteriovenous malformations of the spinal cord as congenital lesions. The findings also indicate that AVMs of the spinal cord produce myelopathy as a result of high blood flow, but that patients with spinal dural AV fistulas develop myelopathy as a result of increased venous pressure in the spinal cord. Magnetic resonance imaging permits demonstration of the presence and site of arteriovenous malformations of the spinal cord and therefore is a valuable and safe, non-invasive technique to investigate patients suspected of having spinal AVMs. Foix-Alajounine syndrome was demonstrated to be due to venous congestion, and not venous thombosis, and therefore, amenable to reversal by treatment of the spinal AVMs. Spinal AVM were shown to recanalize consistently after embolic occlusion. Patients with Von Hippel-Lindau disease were investigated and the following were shown: 1) investigation of the molecular biology of the hemangioblastomas of the central nervous system revealed a homozygous deletion of a portion of the short arm of the third chromosome, demonstrating that these tumors are probably caused by the absence of a tumor suppressing gene, as are familial retinoblastomas. MRI with gadolinium EDTA contrast enhancement was shown to be a sensitive technique of detection for small hemangioblastomas of the central nervous system. Excision of the tumors alone was shown to result in resolution of syringomyelia associated with spinal cord hemangioblastomas. Therefore the tumor-associated syrinx does not need separate treatment.